The present invention relates to a dynamic queue load balancing technique for performing selective assignment of a processing request among queues of a plurality of computers, thereby dynamically performing load balancing. More specifically, the invention relates to the technique that is effective for being applied to the dynamic queue load balancing technique in which a plurality of servers offer the same service and load balancing of client requests is performed among the servers.
As a conventional technique in this field, there is provided a load balancing method that uses a queue between a client and a server.
In this method, a client request is assigned to a queue with the smallest load through a load balancing mechanism, and by copying of the client request from the queue to other queues, load balancing is performed. According to this method, it is possible to achieve load balancing of client requests among the queues. JP-A-2000-56996 discloses this technique.
The disclosed method is the one in which load balancing is achieved through provision of a request scheduling computer equipped with the queue and a request processing computer (server), separately. The request scheduling computer performs queuing and scheduling of a processing request, while the request processing computer performs processing of the request. In this method, when it has taken much time for a certain request processing computer to process a certain processing request, the request is assigned to other request processing computer through the request scheduling computer. Load balancing with other free request processing computer thereby becomes possible.
These techniques aim at reduction of the average response time of a client request. In order to achieve this purpose, when a problem occurs in one of the servers at the time of processing a certain client request, it is so arranged that other server can process the client request. JP-A-7-319834 discloses the technique described above.